Defenseman Justin Falk’s booming voice suddenly cut through the din of today’s intense Sabres practice. “Shut the (expletive) up, you selfish (expletive),” Falk yelled as he skated at winger Evander Kane on the KeyBank Center ice. Falk then shoved Kane before some coaches intervened. Clearly, the Sabres’ wretched 10-win season has ignited emotions. About 30 minutes after the incident, Falk, who was battling Kane in front of the net, was still riled up. “It’s just spur of the moment, emotions are running high,” an agitated Falk said in the dressing room. “This time of year, where we’re at, everyone’s got a situation they’re in, just heat of the moment, boiled over. “To be honest, maybe a little bit more stuff like that is probably what we need, get things going here, get guys playing with a bit more passion, urgency.” Kane also downplayed the incident. “It’s just the heat of the moment,” he said. “It’s guys kind of trying to push each other, make each other better. I think that’s part of the game and you see it from time to time.” Falk said exchanges like Wednesday’s are common.